Generally, there are several types of substances that may be unsuitable or harmful in the environment (environmentally hazardous substances). Some may be harmful to animals via a specific mechanism (such as hormones that may influence the normal reproduction of marine animals), others may be generally toxic (such as cytostatic drugs) while, in the case of antibiotics and antiviral drugs, there may be an increased risk for development of resistant bacteria and viruses if the environment contains antibiotics and antiviral drugs for a substantial amount of time. Environmentally hazardous substances include antibiotics, antifungal and antiviral drugs, NSAID (non-steroid anti-inflammatory drugs), cytostatic drugs, hormones (such as steroid hormones), antidepressants, antipsychotics, and many other pharmaceutical or non-pharmaceutical substances.
Today, much pharmaceutical and biotech research is performed on cells from cultures that grow for a varying amount of time in a medium. In order to prevent bacterial infections which can destroy cell cultures, various types of antibiotics are often added to the growth medium. See “The prophylactic use of antibiotics in cell culture”, Ingrid Kuhlmann, Cytotechnology (1995), pp 95-105. When the cell culture is discarded, it is important to prevent that the antibiotics from the cell culture is released to the environment, which could enhance development of antibiotic resistant bacteria. This may be achieved by heating of the growth medium during autoclaving, if the substances being used are thermosensitive. However, many antibiotics and other hazardous substances are not sufficiently de-graded by this process, and it may therefore be necessary to incinerate the substances in a high temperature oven instead. This can be problematic e.g. in a research institute that can generate very substantial amounts of liquid polluted with antibiotics every day. The disposal of large quantities of waste such as growth media and other liquids with environmentally hazardous substances such as antibiotics to suitable high temperature incinerators can result in high financial costs as well as logistic problems. Therefore, it is desirable to reduce the amount of waste that has to be destroyed to a minimum.
The process of vaporization is widely used to concentrate foods and chemicals as well as to salvage solvents. A solution containing the desired product is fed into the evaporator and passes across a heat source in a reusable vaporization chamber. The applied heat converts the water in the solution into vapor. The vapor is removed from the rest of the solution and is normally condensed before being released, while the now-concentrated solution is either fed into a second evaporator or is removed. An evaporator apparatus used in the present invention generally consists of four units:                a liquid receiving unit for receiving the water solution,        at least one reusable vaporization chamber for heating the water solution so as to vaporize water from said water solution,        a vapor evacuation unit, and        a vapor releasing unit, e.g. a condensation unit, which is connectable to an ambient system, such as a sewage system, for releasing vapor or condensed water during the vaporization process.        
Evaporators can also be used to isolate environmentally hazardous substances which are dissolved in water solutions. An initial vaporization process removes much, but not all, of the water. The removed vapor, or water if a condensation unit is used, can be released into an ambient system, e.g. directly into the ambient air, a sewage system, a water tank or even a ditch. The remaining solution in the reusable vaporization chamber contains the hazardous substances, and can subsequently be taken care of for instance by destruction in an incinerator. This eliminates a potential environmental hazard.
However, there are considerable problems with this method.
Vaporization of the water solution results in fouling with hard deposits on the surfaces of the vaporization chamber, especially when a large portion of the liquid has been vaporized and the concentration of the solvents therefore has increased. It may require costly and labor-intensive cleaning to remove these deposits, or it may even require a replacement of the soiled unit. Another problem with removing much water in the reusable vaporization chamber is that the viscosity of the water solution will gradually increase, which will make it increasingly difficult to transfer the water residue to a waste container. Therefore, before all of the water has been vaporized in the vaporization chamber, the vaporization process is stopped at a certain time, at which the remaining solution in the evaporator is removed from the reusable vaporization chamber for handling as waste and possible destruction. Accordingly, the present method of isolation of substances that are dissolved in water solutions necessarily results in the production of considerable amounts of waste material, which is uneconomic and causes logistical problems.